It is common to use a glass slide to hold a material of interest (sample) when performing Raman or fluorescence microscopy. Referring to FIG. 1, a problem arises in that an interfering spectrum 120 from the glass 102 can overwhelm the desired spectrum 112 from the sample 100, especially if (a) not much sample is present; (b) the probe has a larger spot size than the sample; and/or (c) the sample is transparent and is a weak Raman/fluorescence scatterer. In an attempt to solve this problem, researchers will sometimes wrap the slide in aluminum foil to shield the glass from the laser 110.